Tests: compare the RGB values of colors in the art-style round trip

art_styles_write_the_same_bytes_again failed on Windows (MSVC) on the
Pink swatch: the first save wrote its CMYK equivalent as 0 0.9317
0.1527 0 and the save of the reopened file as 0 0.9389 0.1629 0. The
writer computes the CMYK equivalent of an RGB color from its RGB values,
and the save of the reopened file computes it from the RGB values read
back at four decimals; for this out-of-gamut color the Generic CMYK
conversion moves by more than the test's 0.002 there. On macOS the two
saves of this document differ by at most 0.0016 in these numbers.

The test now blanks the CMYK equivalents of RGB colors (the first four
numbers of `c m y k r g b Xa` and of an RGB gradient stop's
`c m y k r g b 2 ... Bs`) and compares every other number, the RGB
values included. With them blanked, the two saves are identical on
macOS. The large-canvas test's comment also says what such objects are
written as.

crates/eps/src/ai_editing/tests.rs

@@ -5549,7 +5549,8 @@ fn effects_in_a_styled_objects_mask_are_warned_about() {
 }
 
 /// On a large canvas no art style is written (the reader scales the styles of a large canvas):
-/// objects with effects are their drawn look, with a warning.
+/// objects with effects are written as their vector art with their geometry effects applied, with a
+/// warning.
 #[test]
 fn a_large_canvas_writes_no_art_styles() {
     let mut doc = Document::new(20000.0, 100.0);
@@ -5577,7 +5578,23 @@ fn art_styles_write_the_same_bytes_again() {
     assert_eq!(private_data(&doc, &opts()).unwrap().0, private_data(&doc, &opts()).unwrap().0);
     // What is read back is written as it was.
     let again = export_ai_editing(&read_back(&doc), &opts()).unwrap().program;
-    near_lines(&shown(&again), &shown(&first.program));
+    near_lines(&rgb_without_cmyk(&shown(&again)), &rgb_without_cmyk(&shown(&first.program)));
+}
+
+/// `program` with the CMYK equivalents of RGB colors blanked out: the first four numbers of an RGB
+/// color's `c m y k r g b Xa` (or `XA`) and of an RGB gradient stop's `c m y k r g b 2 ... Bs`. A
+/// save of the reopened file computes them again from the RGB values read back at four decimals,
+/// and on some platforms the CMYK conversion moves them by more than [`near_lines`] allows. The RGB
+/// values stay compared.
+fn rgb_without_cmyk(program: &str) -> String {
+    let blank = |line: &str| {
+        let (prefix, rest) = line.strip_prefix("%_").map_or(("", line), |r| ("%_", r));
+        let t: Vec<&str> = rest.split(' ').collect();
+        let color = t.len() == 8 && matches!(t[7], "Xa" | "XA");
+        let stop = t.len() > 8 && t[7] == "2" && t.last() == Some(&"Bs");
+        if color || stop { format!("{prefix}_ _ _ _ {}", t[4..].join(" ")) } else { line.to_string() }
+    };
+    program.lines().map(blank).collect::<Vec<_>>().join("\n")
 }
 
 /// `n` on the first layer of `doc`.